linux-stable.git/fs/proc, branch v5.4.293

fs/procfs: fix the comment above proc_pid_wchan()

2025-04-10T12:29:42+00:00

[ Upstream commit 6287fbad1cd91f0c25cdc3a580499060828a8f30 ]

proc_pid_wchan() used to report kernel addresses to user space but that is
no longer the case today.  Bring the comment above proc_pid_wchan() in
sync with the implementation.

Link: https://lkml.kernel.org/r/20250319210222.1518771-1-bvanassche@acm.org
Fixes: b2f73922d119 ("fs/proc, core/debug: Don't expose absolute kernel addresses via wchan")
Signed-off-by: Bart Van Assche 
Cc: Kees Cook 
Cc: Eric W. Biederman 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

fs/proc: fix softlockup in __read_vmcore (part 2)

2025-02-01T17:18:51+00:00

commit cbc5dde0a461240046e8a41c43d7c3b76d5db952 upstream.

Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the
number of softlockups in __read_vmcore at kdump time have gone down, but
they still happen sometimes.

In a memory constrained environment like the kdump image, a softlockup is
not just a harmless message, but it can interfere with things like RCU
freeing memory, causing the crashdump to get stuck.

The second loop in __read_vmcore has a lot more opportunities for natural
sleep points, like scheduling out while waiting for a data write to
happen, but apparently that is not always enough.

Add a cond_resched() to the second loop in __read_vmcore to (hopefully)
get rid of the softlockups.

Link: https://lkml.kernel.org/r/20250110102821.2a37581b@fangorn
Fixes: 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore")
Signed-off-by: Rik van Riel 
Reported-by: Breno Leitao 
Cc: Baoquan He 
Cc: Dave Young 
Cc: Vivek Goyal 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

proc/softirqs: replace seq_printf with seq_put_decimal_ull_width

2024-12-14T18:44:21+00:00

[ Upstream commit 84b9749a3a704dcc824a88aa8267247c801d51e4 ]

seq_printf is costy, on a system with n CPUs, reading /proc/softirqs
would yield 10*n decimal values, and the extra cost parsing format string
grows linearly with number of cpus. Replace seq_printf with
seq_put_decimal_ull_width have significant performance improvement.
On an 8CPUs system, reading /proc/softirqs show ~40% performance
gain with this patch.

Signed-off-by: David Wang <00107082@163.com>
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

fs/proc: fix compile warning about variable 'vmcore_mmap_ops'

2024-11-17T13:58:52+00:00

commit b8ee299855f08539e04d6c1a6acb3dc9e5423c00 upstream.

When build with !CONFIG_MMU, the variable 'vmcore_mmap_ops'
is defined but not used:

>> fs/proc/vmcore.c:458:42: warning: unused variable 'vmcore_mmap_ops'
     458 | static const struct vm_operations_struct vmcore_mmap_ops = {

Fix this by only defining it when CONFIG_MMU is enabled.

Link: https://lkml.kernel.org/r/20241101034803.9298-1-xiqi2@huawei.com
Fixes: 9cb218131de1 ("vmcore: introduce remap_oldmem_pfn_range()")
Signed-off-by: Qi Xi 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/lkml/202410301936.GcE8yUos-lkp@intel.com/
Cc: Baoquan He 
Cc: Dave Young 
Cc: Michael Holzheu 
Cc: Vivek Goyal 
Cc: Wang ShaoBo 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

proc: add config & param to block forcing mem writes

2024-11-08T15:20:38+00:00

[ Upstream commit 41e8149c8892ed1962bd15350b3c3e6e90cba7f4 ]

This adds a Kconfig option and boot param to allow removing
the FOLL_FORCE flag from /proc/pid/mem write calls because
it can be abused.

The traditional forcing behavior is kept as default because
it can break GDB and some other use cases.

Previously we tried a more sophisticated approach allowing
distributions to fine-tune /proc/pid/mem behavior, however
that got NAK-ed by Linus [1], who prefers this simpler
approach with semantics also easier to understand for users.

Link: https://lore.kernel.org/lkml/CAHk-=wiGWLChxYmUA5HrT5aopZrB7_2VTa0NLZcxORgkUe5tEQ@mail.gmail.com/ [1]
Cc: Doug Anderson 
Cc: Jeff Xu 
Cc: Jann Horn 
Cc: Kees Cook 
Cc: Ard Biesheuvel 
Cc: Christian Brauner 
Suggested-by: Linus Torvalds 
Signed-off-by: Linus Torvalds 
Signed-off-by: Adrian Ratiu 
Link: https://lore.kernel.org/r/20240802080225.89408-1-adrian.ratiu@collabora.com
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

fs/proc: fix softlockup in __read_vmcore

2024-07-05T07:08:18+00:00

commit 5cbcb62dddf5346077feb82b7b0c9254222d3445 upstream.

While taking a kernel core dump with makedumpfile on a larger system,
softlockup messages often appear.

While softlockup warnings can be harmless, they can also interfere with
things like RCU freeing memory, which can be problematic when the kdump
kexec image is configured with as little memory as possible.

Avoid the softlockup, and give things like work items and RCU a chance to
do their thing during __read_vmcore by adding a cond_resched.

Link: https://lkml.kernel.org/r/20240507091858.36ff767f@imladris.surriel.com
Signed-off-by: Rik van Riel 
Acked-by: Baoquan He 
Cc: Dave Young 
Cc: Vivek Goyal 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

procfs: block chmod on /proc/thread-self/comm

2023-09-23T08:59:55+00:00

commit ccf61486fe1e1a48e18c638d1813cda77b3c0737 upstream.

Due to an oversight in commit 1b3044e39a89 ("procfs: fix pthread
cross-thread naming if !PR_DUMPABLE") in switching from REG to NOD,
chmod operations on /proc/thread-self/comm were no longer blocked as
they are on almost all other procfs files.

A very similar situation with /proc/self/environ was used to as a root
exploit a long time ago, but procfs has SB_I_NOEXEC so this is simply a
correctness issue.

Ref: https://lwn.net/Articles/191954/
Ref: 6d76fa58b050 ("Don't allow chmod() on the /proc// files")
Fixes: 1b3044e39a89 ("procfs: fix pthread cross-thread naming if !PR_DUMPABLE")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Aleksa Sarai 
Message-Id: <20230713141001.27046-1-cyphar@cyphar.com>
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps

2023-02-22T11:50:28+00:00

commit 3489dbb696d25602aea8c3e669a6d43b76bd5358 upstream.

Patch series "Fixes for hugetlb mapcount at most 1 for shared PMDs".

This issue of mapcount in hugetlb pages referenced by shared PMDs was
discussed in [1].  The following two patches address user visible behavior
caused by this issue.

[1] https://lore.kernel.org/linux-mm/Y9BF+OCdWnCSilEu@monkey/


This patch (of 2):

A hugetlb page will have a mapcount of 1 if mapped by multiple processes
via a shared PMD.  This is because only the first process increases the
map count, and subsequent processes just add the shared PMD page to their
page table.

page_mapcount is being used to decide if a hugetlb page is shared or
private in /proc/PID/smaps.  Pages referenced via a shared PMD were
incorrectly being counted as private.

To fix, check for a shared PMD if mapcount is 1.  If a shared PMD is found
count the hugetlb page as shared.  A new helper to check for a shared PMD
is added.

[akpm@linux-foundation.org: simplification, per David]
[akpm@linux-foundation.org: hugetlb.h: include page_ref.h for page_count()]
Link: https://lkml.kernel.org/r/20230126222721.222195-2-mike.kravetz@oracle.com
Fixes: 25ee01a2fca0 ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps")
Signed-off-by: Mike Kravetz 
Acked-by: Peter Xu 
Cc: David Hildenbrand 
Cc: James Houghton 
Cc: Matthew Wilcox 
Cc: Michal Hocko 
Cc: Muchun Song 
Cc: Naoya Horiguchi 
Cc: Vishal Moola (Oracle) 
Cc: Yang Shi 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

sysctl: add a new register_sysctl_init() interface

2023-02-06T06:52:48+00:00

commit 3ddd9a808cee7284931312f2f3e854c9617f44b2 upstream.

Patch series "sysctl: first set of kernel/sysctl cleanups", v2.

Finally had time to respin the series of the work we had started last
year on cleaning up the kernel/sysct.c kitchen sink.  People keeps
stuffing their sysctls in that file and this creates a maintenance
burden.  So this effort is aimed at placing sysctls where they actually
belong.

I'm going to split patches up into series as there is quite a bit of
work.

This first set adds register_sysctl_init() for uses of registerting a
sysctl on the init path, adds const where missing to a few places,
generalizes common values so to be more easy to share, and starts the
move of a few kernel/sysctl.c out where they belong.

The majority of rework on v2 in this first patch set is 0-day fixes.
Eric Biederman's feedback is later addressed in subsequent patch sets.

I'll only post the first two patch sets for now.  We can address the
rest once the first two patch sets get completely reviewed / Acked.

This patch (of 9):

The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

Today though folks heavily rely on tables on kernel/sysctl.c so they can
easily just extend this table with their needed sysctls.  In order to
help users move their sysctls out we need to provide a helper which can
be used during code initialization.

We special-case the initialization use of register_sysctl() since it
*is* safe to fail, given all that sysctls do is provide a dynamic
interface to query or modify at runtime an existing variable.  So the
use case of register_sysctl() on init should *not* stop if the sysctls
don't end up getting registered.  It would be counter productive to stop
boot if a simple sysctl registration failed.

Provide a helper for init then, and document the recommended init levels
to use for callers of this routine.  We will later use this in
subsequent patches to start slimming down kernel/sysctl.c tables and
moving sysctl registration to the code which actually needs these
sysctls.

[mcgrof@kernel.org: major commit log and documentation rephrasing also moved to fs/proc/proc_sysctl.c                  ]

Link: https://lkml.kernel.org/r/20211123202347.818157-1-mcgrof@kernel.org
Link: https://lkml.kernel.org/r/20211123202347.818157-2-mcgrof@kernel.org
Signed-off-by: Xiaoming Ni 
Signed-off-by: Luis Chamberlain 
Reviewed-by: Kees Cook 
Cc: Iurii Zaikin 
Cc: "Eric W. Biederman" 
Cc: Peter Zijlstra 
Cc: Greg Kroah-Hartman 
Cc: Paul Turner 
Cc: Andy Shevchenko 
Cc: Sebastian Reichel 
Cc: Tetsuo Handa 
Cc: Petr Mladek 
Cc: Sergey Senozhatsky 
Cc: Qing Wang 
Cc: Benjamin LaHaise 
Cc: Al Viro 
Cc: Jan Kara 
Cc: Amir Goldstein 
Cc: Stephen Kitt 
Cc: Antti Palosaari 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Clemens Ladisch 
Cc: David Airlie 
Cc: Jani Nikula 
Cc: Joel Becker 
Cc: Joonas Lahtinen 
Cc: Joseph Qi 
Cc: Julia Lawall 
Cc: Lukas Middendorf 
Cc: Mark Fasheh 
Cc: Phillip Potter 
Cc: Rodrigo Vivi 
Cc: Douglas Gilbert 
Cc: James E.J. Bottomley 
Cc: Jani Nikula 
Cc: John Ogness 
Cc: Martin K. Petersen 
Cc: "Rafael J. Wysocki" 
Cc: Steven Rostedt (VMware) 
Cc: Suren Baghdasaryan 
Cc: "Theodore Ts'o" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Eric Biggers 
Signed-off-by: Sasha Levin

mm: /proc/pid/smaps_rollup: fix no vma's null-deref

2022-10-29T08:20:36+00:00

Commit 258f669e7e88 ("mm: /proc/pid/smaps_rollup: convert to single value
seq_file") introduced a null-deref if there are no vma's in the task in
show_smaps_rollup.

Fixes: 258f669e7e88 ("mm: /proc/pid/smaps_rollup: convert to single value seq_file")
Signed-off-by: Seth Jenkins 
Reviewed-by: Alexey Dobriyan 
Tested-by: Alexey Dobriyan 
Signed-off-by: Greg Kroah-Hartman